A method and a device are known e.g. from WO 2009/037089 A1.
Accurate monitoring of chemical and/or physical properties of operating substances in machine installations is becoming increasingly important. This applies in particular to machine installations on board floating entities such as, e.g., ships or offshore platforms. For example, new EU directives have led to the introduction of sulfur limit values for ship fuels that must be complied with by ships in ports or in certain maritime or inland waterways. When traveling in said waters, ships can be subject to inspections to verify whether only fuel having a sulfur content below the prescribed limit value is being used.
On the world's oceans outside of these waters it continues to be permissible to burn fuel having any sulfur content. Low-sulfur fuel is more expensive than fuel with a high sulfur content, so ships are operated over the greatest part of the route with cheap sulfur-containing fuel and low-sulfur fuels are used only in areas subject to special limit values. This means that in the future ships will bunker fuels of different qualities and that said fuels will also be mixed with one another as necessary (a process referred to as “blending”).
The new EU directives make the proper keeping of logbooks with details of fuel changeover a condition for ships being able to enter ports of the EU community. Samples of ship fuels can be taken during inspections and analyzed to determine their sulfur content. Ship personnel are therefore required not only to monitor the fuel supplied to the machines during operation, but also to check beforehand the quality of the fuel at the time of refueling.
A fuel system having a measuring and evaluation device for online determination of the sulfur content of the fuel with the aid of infrared spectroscopy is already known from WO 2009/037089 A1. For this purpose the fuel is irradiated in a measuring cell with light from an infrared (IR) light source. The spectrum of the light transmitted through the fuel or reflected by the fuel is measured by means of a spectrometer and the measured spectrum analyzed with the aid of algorithms and using a calibration model.
Already known from WO 2007/093500 A1 is a measuring system in which the sulfur content of a ship fuel is determined with the aid of IR spectroscopy and the lubricant supply to the cylinders of a combustion engine driven by means of said fuel is controlled as a function thereof.
In addition to determining the sulfur content in fuels there exists a need in many machine installations to determine chemical and/or physical properties of a plurality of other operating substances such as e.g. lubricants in bearings or hydraulic fluids as part of preventive maintenance measures or in order to optimize operation.